The present invention relates to a tubular artificial sausage casing based on fiber-reinforced cellulose and to a process for producing this casing. Such sausage casings are also referred to as fibrous casings.
As is known, sausage casings of this kind are completely saturated with water before they are stuffed with sausage meat. For this purpose, the sausage casings are placed in a water bath for about 15 to 30 minutes. After soaking, the cellulose tube has a water content of from 80 to 120%, based on the cellulose. This value is called the "swelling value" and refers to the maximum water-retention capacity. The moisture content of cellulose casings is usually indicated in percent by weight, based on the total weight of the casing. Sausage meat is pressed into the completely soaked sausage casing and, in the process, the casing, which has an increased flexibility due to its high water content, is expanded by about 10 to 15% in the circumferential direction to its socalled "stuffing diameter", at a stuffing pressure which is not too high.
To expand the sausage casing it is necessary to retard its running off from the stuffing horn during stuffing with sausage meat. For this purpose, the casing is retained at the orifice of the stuffing horn, for example, by means of a casing clamp, and a restraining force is thus generated. The higher this restraining force, the higher the internal pressure in the sausage casing rises and the larger the outside diameter of the sausage will be. In practice it has generally been shown that the conventional fiber-reinforced casings have a specific, most favorable minimum diameter upon filling, which depends on their diameter in the dry state (moisture content from 8 to 12%). When a sausage casing reaches this so-called "stuffing diameter" it closely contacts the sausage meat, and the sausage thus obtained looks plump and crease-free. The stuffing diameter is set down in tables by the manufacturers of the casings for each size and type of casing and serves as a guide to the processors in the production of sausages. If a casing is not filled up to the recommended stuffing diameter, the resulting sausage looks crinkled and has a non-uniform cross section. On the other hand, if the sausage casing is filled to substantially exceed the stuffing diameter, there is an increased risk of bursting during filling or during the subsequent scalding or smoking process.
A specific restraining force which causes a rise of the internal pressure is necessary to expand the sausage casing to its stuffing diameter. To obtain a sausage showing the highest possible uniformity of diameter, the restraining force must remain as constant as possible, which can often be controlled only with difficulty. It is therefore the most important object of this invention to find a way of reducing variations of the stuffing diameter in the filling process.
The restraining force or the internal pressure, respectively, which is required to stuff a sausage casing to its full size (stuffing diameter) is non-adjustably set in modern automatic stuffing machines for the conventional completely soaked sausage casings. If a so-called "ready-to-stuff" sausage casing of fiber-reinforced cellulose is used, i.e., a casing having sufficient moisture content that further moisture need not be added prior to stuffing, this casing is less flexible due to its low water content. Since the recommended stuffing diameter is independent of whether the sausage casing has been completely soaked prior to filling or has a lower moisture content, the internal pressure chosen to attain the same stuffing diameter, as in the case of a completely soaked casing, must be substantially higher when a ready-to-stuff casing type is filled. For a moisture content of only 29 to 42%, the internal pressure must correspond to two to three times the internal pressure used for filling a completely soaked casing, as indicated, for example, in German Patent No. 27 45 991.
These values, however, apply to the hitherto customary fiber-reinforced tubular cellulose casings oily, the expansion behavior of which is described in German Patent No. 27 45 991. The expansion behavior of these sausage casings, hereinafter called "standard casings", is also evident from the fact that they shrink by 1 to 2% in the longitudinal direction and by 2 to 3% in the transverse direction, after having been completely soaked in water (40.degree. to 50.degree. C., for about 30 minutes).
A change of the restraining force on the filling machine for the purpose of processing different sausage casing types, however, entails an undesirable expenditure of work for the processor. In addition, the casing material is heavily mechanically stressed when the restraining force is increased by two to three times its value and, as a result, the risk of bursting rises and more frequent interruptions of production must be expected during processing.
In the filling of ready-to-stuff cellulose casings, the internal pressure could only be reduced to the values applicable to completely soaked casings, if uniformity of diameter would be dispensed with and tightly stuffed sausages were not important.